Halogenated coal acids



HALOGENATED COAL ACIDS Herbert B. Rickert, Midland, Mich., assignor toThe Dow Chemical Company, Midland, Micln, a corporation of Delaware NoDrawing. Application September 19, 1957 Serial N 684,838

6 Claims. (Cl. ass-s15 The present invention pertains and contributes tothe chemical arts. In particular, it is concerned with the provision ofcertain halogenated organic compounds. More particularly, this inventionhas reference to the chlorinated and brominated polycarboxylic acidsthat are derived from the oxidation of coal and the like carbonaceousmaterials which, for convenience, are hereinafter referred to as beingcoal acids.

Coal acids are known compounds which, as has been indicated, may bederived from the oxidation of coal. The coal acids that are utilized inthe practice of the present invention, for example, may be identicalwith or similar to those which may be obtained by the oxidation withgaseous oxygen, which may be contained in the air, of an aqueousalkaline slurry of a finely divided carbonaceous material selected fromthe group consisting of coal and coke that has been obtained by thecarbonization of coal at temperatures beneath about 700 C. Coal acidsthat have been prepared by the nitric acid oxidation of suitablecarbonaceous materials are also generally satisfactory, as areequivalent synthetic mixtures. Such coals that are of the varietiesknown as anthracite, bituminous, sub-bituminous and lignite and otherlow grade coals are generally suitable for the production of coal acids.Satisfactory cokes are those produced according to conventionaltechniques from coal at a temperature beneath about 700 C. Theutilization of of halogens of atomic number from 17 to 35, i.e. chlorine2,929,838 Patented Mar. 22, 1960 and bromine.

According to the present invention, halogenated coal acids may beobtained by dissolving the free coal acids in water so that theresulting aqueous solution has a concentration between about 5 and 40percent by weight (preferably between about and 25 percent by weight);

higher coking temperatures frequently causes the cokes then subjectingthe coal acids in aqueous solution to the action of a halogenatingagent, preferably free chlorine or bromine, at a temperature from about20 to 95 C. (advantageously, not in excess of 60 C.) while maintainingthe reaction mass at a pH in the range from about 3 to 9 (beneficiallyin the acidic range from about 4 to 7) until the desired content ofcombined halogen has been obtained in the halogenated coal acidsproduct. Most advantageously, the aqueous solution of the free coalacids may be neutralized with an alkali metal hydroxide (such as sodiumhydroxide) prior to halogenation so that initially the solution has aneutral or slightly alkaline pH of about 7 or so and the incipienthalogenation is accomplished on the dissolved coal acids in an alkalimetal salt form. The halogenated coal acids may be recovered in anydesired manner from the reaction mass subsequent to their halogenationafter the reaction mass has been acidified to a pH ,of l or so.Conveniently the halogenated coal acids product may be removed from theacidified reaction mass by solvent extraction tech-v niques, using suchsolvents as methyl ethyl ketone and the like for the purpose. Thehalogenated coal acids are then isolated from solution in the extractingsolvent by conventional distillation or stripping techniques.

Any desired content of combined halogen up to nearly the uppertheoretical limit may be effected in the foregoing manner. Of course,the particular halogen (or pera'ture that is employed, the pH that ismaintained in The free coal acids product is a hygroscopic, usuallyyellowish, essentially water soluble material that is be lieved to besubstantially comprised of various aromatic polycarboxylic acids. Theaverage molecular weight of the coal acids that are ordinarily obtainedis generally from about 200 to 300; frequently being in the neighborhoodof 250-270. Their average equivalent weight is generally about 80. It isseldom less than 70 or more than 90. The coal acids ordinarily appear tohave an average of 2.5 to 5 carboxylic group per molecule with anapparent average of 3 to 4 being common. While their exact chemicalnature and constitution may be somewhat conjectural, they evidentlycontain considerable quantities of triand tetra-carboxylic benzene acidsas well as aromatic acids having more complex nuclei. Frequently, forexample, the greatly preponderant proportion of aromatic nuclei obtainedin coal acids prepared in the described fashion have been found toconsist of methylnaphthalene, benzene, biphenyl, naphthalene,phenanthrene, benzophenone and various alkyl benzene, including toluene,nuclei. y It is the principal objective of the present invention toprovide, as new and useful compositions of matter, halogenated coalacids, particularly the coal acids that have been halogenated with ahalogen selected from the group the solution, the quantity of thehalogenating agent that is utilized, and, as is apparent, the content ofcombined halogen that is desired to be finally obtained in thesubstituted product. When the reaction is conducted at temperatureslower than those in the indicated ranges, it may be found to proceed ata slower rate than is desirable. At temperatures higher than thoseindicated, an intolerably high proportion of the coal acids may be foundto be destroyed. In this concention, even at temperatures between 60 andC., greater destruction of the coal acids than is desirable may beencountered. Hence, the preferred indicated lower temperature range maybeneficially be utilized for conducting the reaction. If the solutionbeing halogenated is maintained ata pH that is either too high or toolow, the rate of halogenation is generally found to be slower thanrequired for practical operations.

' Although solutions of the coal acids that are more dilute than 5percent by weight may be halogenated,.the volumetric efiiciency of thereaction is undesirably lower at such low concentrations. At startingconcentrations of the dissolved free coal acids higher than thoseindicated, difiiculty may be encountered with precipitation of the acidsat the commencement ofthe reaction. For this reason, it is preferred tooperate with aqueous solutions which are'prepared so as to haveconcentrations of the 3 dissolved free coal acids that are not greatlyin excess of about 25 percent by weight.

The halogenated coal acids products of the present invention aregenerally .water soluble materials that also have better solubility invarious organic materials (such as mixtures of-glycols, and fatty acids)than do the unmodified free coal .acids. They are generally hygroscopic,yellowish to brown colored powders having apparent bulk densities lessthan one gram per cubic centimeter. They are found to be soluble inwater, acetone and methanol; partly soluble in ethyl acetate; andinsoluble in benzene, petroleum ether and carbon tetrachloride. Themolecular weight of the halogenated coal acids obviously -depends uponthat of the starting material and the extent of halogenation involved,as well .as the particular halogen that .is substituted in the free coalacids. Their average equivalent weight is generally somewhat higher thanthat of the free coal acids. The substitution of the halogen is believedto occur on both the nucleus and thecarboxylic substituents of the coalacids molecules. Frequently about commensurate degrees of nuclear andside chain halogenation are obtained inthe products of the presentinvention. In addition to many other uses, the halogenated coal acidproducts of the present'invention, particularly the chlorinatedderivatives, have marked bi ological activity and are found to haveexcellent effectiveness against microorganisms especially, for example,as fungicides.

The invention will be further illustrated in and by the followingexamples which are not intended to be limiting thereof and wherein,unless otherwise indicated, all parts and percentages are to be taken byweight.

Example I About 50 grams of free coal acids having an average molecularweight of about 270 and an average equivalent weight of about 83 weredissolved in 221 grams of distilled water. The resulting solution wasfiltered in order to remove about 1.5 grams of relatively insolublematerial. The filtrate was then neutralized with 50 percent caustic(NaOI-l) aqueous solution to adjust its pH to about 7. The color of theneutralized solution had a numerical rating of about on the GardnerColor Scale.

Elemental chlorine was then sparged into the neutralized solution.Within 7 minutes after the initial intro duction of chlorine, thetemperature of the reaction mass increased from an initial value ofabout 28 C. to'a temperature of about35 C. at which level it remainedfor about 45 minutes. After one hour of reaction, the temperaturedeclined to about 32 C. At this point the pH of the reaction mass wasfound to be about 3.5. Twentyeight m1. of the 50 percent causticsolution were then added and the chlorination continued at the samerate. After 22 minutes of the continued chlorination, the temperaturerose to about 45 C. and then fell gradually to about 32 C. (within anadditional 15 minute period) at which time additional caustic was againadded. The chlorine addition was then continued until the temperaturecycle again repeated, at the end of which the pH was again adjusted withthe caustic solution. After a numberof neutralizations with caustic andchlorine additions, a point was attained where very little heat wasgenerated by the caustic neutralization. At this point, which was about7 hours after the initial introduction of chlorine, the reaction wasterminated. The'highest temperature that had been reached during theentire chlorination was about 49 C. A total quantity of about ,124 ml.of the caustic solution had been .used. At the termination of thereaction, the reaction mass containing the chlorinated coal acidsinaqueous solution had a pH of about 6.6 and a Gardner Color Numberbetween .8 and-9.

About 22 ml. of concentrated sulfuric. acid (H 50 ,wasthen added to thehalogenated reaction mass. The

pH of the acidified solution was about 0.4. The acidified solution wasthen twice extracted with separate volumes of methyl ethyl ketone toobtain two separate quantities of the chlorinated coal acids in methylethyl ketone solution. The methyl ethyl ketone solutions were thencombined and the solvent stripped off under vacuum. About 51 grams ofchlorinated coal acids were thereby obtained. The chlorinated producthad an equivalent weight ofabout 111. It was found to contain about 28.1percent of combined chlorine.

Example 2 In a manner similar to that described in the foregoingexample, about 300 parts of coal acids similar to those employed inExample 1 were dissolved in 1200 parts of distilled water and filteredto remove insoluble materials. The pH was adjusted to 7 with 50 percentaqueous caustic solution. The neutralized solution was then chlorinatedby sparging free chlorine therethrough. The chlorination was continuedfor about 10.5 hours at an average temperature of 54 C. During thisperiod a total of 340 parts of free chlorine and 280 parts of NaOH wereemployed. The reaction mass, after termination of the reaction, wasextracted three times with methyl ethyl ketone to recover thechlorinated coal acids. 'The resulting solutions were mixed and strippedunder vacuum to yield about 244 parts of chlorinated coal acidscontaining about 12.8 percent of combined chlorine. The chlorinated coalacids product was a yellowish colored solid.

Example 3 The general procedure of the first two examples was followedto chlorinate about 50 grams of free coal acids of the same type as usedin the foregoing which were dissolved in 200 grams of water, with theexception that the chlorination was conducted at an average temperatureof 94 C. At the end of about 3.4 hours thereaction was terminated andabout 25 grams of chlorinated coal acids were recovered in the aboveindicated manner. The chlorinated coal acids product contained about22.8 percent by weight of combined chlorine and had an equivalent weightof 94.

Example 4 The procedure of Example 3 was repeated to chlorinate about 80grams of free coal acids that were dissolved in 320 grams of water withthe exception that the average temperature of the reaction was about 49C. and the chlorination was continued .for a 14 hour period. Thechlorinated product contained about 27.7 percent of combined chlorineand had a molecular weight'of 297.

Example 5 The foregoing procedure was essentially repeated with a 15percent aqueous solution of 600 grams of free coal acids that had beenfiltered and neutralized. The dis solved coal acids were chlorinated for8.8 hours at an average temperature of 50 C. About 414 grams of achlorinated coal acids product was recovered. The halogenated acidsproduct contained about 12.4 percent of combined chlorine and had amolecular weight of about Example 6 Benicillinm rlzfgilatrlm whenincorporatedin the culture medium as an antimicrobial agent at about 0.1percent concentration.

Example 7 The procedure of Example 6 was repeated excepting to conductthe chlorination for a total period of 6 hours at 42 C. About 48 gramsof chlorinated coal acids were obtained having a combined chlorinecontent of about 30.5 percent.

Example 8 When the general procedure that is set forth in the foregoingexamples is repeated, excepting to perform the halogenation withelemental bromine, equivalent results and commensurate products areobtained. The brominatrons may frequently require a longer period oftime than the corresponding chlorinations. Mixed halogen products canalso be obtained by performing the halogenation with either mixtures ofchlorinating or brominating agents or by separately performing thechlorination and halogenation in any desired sequential order.

Example 9 Using an apparatus in which a pH reading could be continuouslyobtained, a charge of about 1 equivalent of free coal acids in 900 gramsof water was prepared. The free coal acids product had an averagemolecular weight (as determined by boiling point evaluation techniques)of about 284, an apparent equivalent weight of about 84.6, and uponanalysis, was found to contain about 54.36 percent by weight of combinedcarbon; about 3.10 percent by weight of combined hydrogen; about 0.52percent by weight of combined nitrogen; and about 0.16 percent by weightof combined sulfur. The carbon-to-hydrogen ratio in the free coal acidsproduct was about 1.46:1. It had an average functionality, or number ofcarboxylic groups per molecule, of about 3.36.

The prepared coal acids solution was neutralized with about a 90 ml.volume of a 40 percent aqueous sodium hydroxide solution. After theinitial neutralization, about 122 grams of chlorine and 185 ml. of the40 percent sodium hydroxide solution were added uniformly over a periodof about 5.5 hours, while the reaction mass was maintained at atemperature between about 18 and 24 C. The pH of the reaction mass waskept between about 4.7 and 7.5 during the reaction period. After thetermination of the reaction, the reaction mass was acidified withconcentrated sulfuric acid to a pH of about 1 whereupon it was extractedthree times with separate 200 ml. portions of methyl ethyl ketone. Themethyl ethyl ketone extractant was then stripped off under vacuum togive about 64 grams of a tan powder that had a combined chlorine contentof about 14.2 percent and an equivalent weight of about 106. The driedsample had an apparent bulk density of about 0.80 gram per cubiccentimeter. The above product is found to have about the same biologicalactivity and other utilities as that of Example 6.

Example Using the procedure of Example 9 and employing similar free coalacids product for the reaction, a starting solution of about 1.5equivalents of the free coal acids dissolved in about 1040 grams ofwater was prepared. The coal acids solution was initially neutralizedwith about 110 ml. of the 40 percent aqueous solution of sodiumhydroxide. After the initial neutralization, about 250 grams of bromineand 90 ml. of the 40 percent sodium hydroxide solution were uniformlyadded over a period of about 4% hours while the reaction mass wasmaintained at a temperature between about 22 and 36 C. and a pH of from5.3 to 7.1. At the termination of the reaction, the reaction mass wasacidified with concentrated sulfuric acid to a pH of about 1. It wasthen extracted with methyl ethyl ketone and the extract dried to giveabout 138 grams of a dark brown powder product that contained about 21.4percent of combined bromine and had an equivalent weight of about 106.The brominated coal acids product had an apparent bulk density of about0.73 gram per cubic centimeter.

Since certain changes and modifications in the prac tice of the presentinvention can readily be entered into without substantially departingfrom its intended spirit and scope, it is to be fully understood thatthe foregoing description and specification be interpreted and construedas being merely illustrative of the invention which in no sense ormanner is to be understood as being limited to or restricted by thespecific preferred embodiments therein described but is to be viewed ascomprehending the scope and purview that is set forth and defined in thehereto appended claims.

What is claimed is:

1. Halogenated coal acids containing up to about 45 weight percent,based on the weight of the composition, of combined halogen wherein thehalogen substituents are selected from the group of halogens consistingof chlorine, bromine and their mixtures; said coal acids being thewater-soluble, mixed aromatic polycarboxylic acids that are the productsof the oxidation of carbonaceous materials, which acids typically havean average molecular weight of from 200 to 300, and average apparentequivalent weight of from to 90, and contain an average of from about2.5 to 5 carboxylic groups per aromatic nucleus in their molecule.

2. Halogenated coal acids containing up to about 45 weight percent,based on the weight of the composition, of combined halogen wherein thehalogen substituents are selected from the group of halogens consistingof chlorine, bromine and their mixtures; said coal acids being thewater-soluble, mixed aromatic, polycarboxylic acids that are theproducts of the oxidation of coal, which acids typically have an averagemolecular weight of from 200 to 300, and average apparent equivalentweight of from 70 to 90, and contain an average of from about 2.5 to 5carboxylic groups per aromatic nucleus in their molecule.

3. Halogenated coal acids as delineated in claim 2 and containingbetween about 10 and 35 percent by weight, based on the weight of thecomposition, of combined chlorine.

4. Halogenated coal acids as delineated in claim 2 and containingbetween about 10 and 45 percent by weight, based on the weight of thecomposition, of combined bromine.

5. Halogenated coal acids in accordance with the composition that is setforth in claim 2, wherein the combined halogen is chlorine.

6. Halogenated coal acids in accordance with the composition that is setforth in claim 2, wherein the combined halogen is bromine.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Wagner et al.: Synthetic Organic Chemistry. pp. 102-

1. HALOGENATED COAL ACIDS CONTAINING UP TO ABOUT 45 WEIGHT PERCENT,BASED ON THE WEIGHT OF THE COMPOSITION, OF COMBINED HALOGEN WHEREIN THEHALOGEN SUBSTITUENTS ARE SELECTED FROM THE GROUP OF HALOGENS CONSISTINGOF CHLORINE, BROMINE AND THEIR MIXTURES, SAID COAL ACIDS BEIGN THEWATER-SOLUBLE, MIXED AROMATIC POLYCARBOXYLIC ACIDS THAT ARE THE PRODUCTSOF THE OXIDATION OF CARBONACEOUS MATERIALS, WHICH ACIDS TYPICALLY HAVEAN AVERAGE MOLECULAR WEIGHT OF FROM 200 TO 300, AND AVERAGE APPARENTEQUIVALENT WEIGHT OF FROM 70 TO 90, AND CONTAIN AN AVERAGE OF FROM ABOUT2.5 TO 5 CARBOXYLIC GROUPS PER AROMATIC NUCLEUS IN THEIR MOLECULE.